In an IP multimedia subsystem (IP Multimedia Subsystem, IMS) network, a multimedia service of a user such as a voice over LTE (Voice Over Long Term Evolution, VoLTE) service may be controlled by a plurality of different application servers (Application Server, AS), such as a service centralization and continuity application server (Service Centralization and Continuity Application Server, SCC AS) and an anchor AS. A charging apparatus in the IMS network may correlate charging messages reported by a plurality of ASs, to obtain a charging session corresponding to a same service; and then performs charging.
In the prior art, ASs may be provided by different manufacturers, and ASs of different manufacturers support different charging capabilities. For example, some ASs have an online charging capability, and some ASs have an offline charging capability. Therefore, the charging apparatus cannot learn of charging capabilities of a plurality of ASs triggered by a same service, and consequently cannot perform unified charging based on charging messages of all the ASs, causing a user charging error.